SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c450665a37a2688644c7510cff96e167329c8a3bf79f76b3304b02152acbd827' 
  AND token = 'TbJLWIkohtgenoySd3daZymvDMKH6kwWJFeGk0K7VI4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}